A timecode superimposed on an image signal includes LTC (Linear Timecode), which is, as a consequence of the biphasemark modulation, recorded in the band of audio frequencies, and VITC (Vertical Interval Timecode), which is, as a consequence of the NRZ modulation, transmitted at vertical intervals.
These timecodes are subject to the occurrence of errors (change of the data content), which is caused by defective retrieval or transmission when reproduced by a reproducing apparatus or transmitted. Such errors cause the accuracy of the timecodes to degrade, therefore it is necessary to detect with high accuracy any error occurred in the timecodes. To be able to detect the errors will offer options such as choosing not to use any erroneous timecode or amending any erroneous portion in the timecode by applying a predetermined processing thereto.
In this regard, the VITC includes in the data thereof CRC code (Cyclic Redundancy Checking Code), by which the occurrence of errors can be detected with high accuracy. However, no methods or structures for detecting errors in the LTC have ever been implemented, and neither has any effective suggestion been advanced.
Therefore, a main object of the present invention is to provide a method of and an apparatus for transmitting a timecode capable of effectively detecting errors occurred in the LTC.